I'm not sure but I think that if I fix the JS errors on these pages the problem will be solved and the images will open normally. Note that on all other browsers it works fine (Firefox, Chrome, Safari, IE9).

The page returns some other errors too but they're the whole time there. I think there's a conflict caused by all the JS libraries loaded by my Plugins (System - RokBox & YOOeffects), Joomla template, VirtueMart & VirtueMart template (jquery and mootools are both loaded).